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Lava fountaining dynamics on 4 of May during the 2021 Geldingardalir eruption, Reykjanes Peninsula, Iceland.

Jóna Sigurlína Pálmadóttir1, Thorvaldur Thordarsson1, Bruce Frank Houghton2, Eva P. S. Eibl3, Caroline Michelle Tisdale 2

  • Affiliations: 1Faculty of Earth Sciences, University of Iceland, Reykjavik, Iceland; 2Earth Sciences, University of Hawaii, Honolulu, USA; 3Institute for Geosciences, University of Potsdam, Germany

  • Presentation type: Poster

  • Presentation time: Tuesday 16:30 - 18:30, Room Poster Hall

  • Poster Board Number: 231

  • Programme No: 1.6.10

  • Theme 1 > Session 6

Abstract

On 19 March 2021, an eruption began in the Fagradalsfjall volcanic system in Iceland, marking the first lava emission on the Reykjanes Peninsula in 781 years. The 2021 Geldingardalir eruption featured nearly 7000 short-lived fountaining episodes, exhibiting an unusual diversity of episodic behaviors. This study focuses on the third phase of the eruption, particularly the period from May 2 to June 10, 2021, when pulsating episodes occurred with exceptional frequency. Lava fountaining activity on 4 May was quantified, analyzed, and interpreted, with a focus on videos captured with a 4K camera between 16:00 and 17:00 GMT. Pulse height, pyroclast exit velocity, and fountain height were quantified, with fountaining heights ranging from 120 to 160 meters and episode durations between 164 to 312 seconds. The pyroclast exit velocities measurements ranged from 16.3 to 20.2 m/s.This study also identifies a link between ongoing fountaining activity and volcanic tremor, showing that tremor episodes began shortly before, and lasted slightly longer than, visible fountaining. The fountaining frequency on May 4 averaged 6-8 episodes per hour, with a mean episode duration of 5.5 minutes (±1.1 min) and repose intervals averaging 2.5 minutes (±0.5 min).